Micromechanic structure and method for making the micromechanic structure

Abstract

A micromechanic structure includes a substrate, an adhesion layer arranged on the substrate, a first metal layer arranged on the adhesion layer, a ferroelectric layer arranged on the first metal layer and including lead zirconate titanate, and a second metal layer arranged on the ferroelectric layer, wherein the lead concentration of the ferroelectric layer decreases in a stepped manner with increasing distance from the first metal layer such that the ferroelectric layer includes a plurality of partial layers in which the lead concentration is respectively uniform.

What is claimed is: 
     
         1 . A micromechanic structure comprising:
 a substrate;   an adhesion layer arranged on the substrate;   a first metal layer arranged on the adhesion layer;   a ferroelectric layer arranged on the first metal layer and including lead zirconate titanate, a lead concentration of the ferroelectric layer decreasing in a stepped manner with an increasing distance from the first metal layer such that the ferroelectric layer includes a plurality of partial layers in which the lead concentration is respectively uniform; and   a second metal layer arranged on the ferroelectric layer.   
     
     
         2 . The micromechanic structure according to  claim 1 , wherein a thickness of each of the plurality of partial layers is in a range from 100 nm to 900 nm. 
     
     
         3 . The micromechanic structure according to  claim 1 , wherein a thickness of each of the plurality of partial layers is in a range from 400 nm to 600 nm. 
     
     
         4 . The micromechanic structure according to  claim 1 , wherein a thickness of each of the plurality of partial layers is 500 nm. 
     
     
         5 . The micromechanic structure according to  claim 1 , wherein a thickness of the ferroelectric layer is in a range from 200 nm to 5000 nm. 
     
     
         6 . The micromechanic structure according to  claim 1 , wherein the ferroelectric layer has a pyroelectric coefficient higher than 1.5*10-4 C/(m 2 K). 
     
     
         7 . The micromechanic structure according to  claim 1 , wherein:
 in the ferroelectric layer   c(Pb)/(c(Zr)+c(Ti)) is in a range from 0.9 to 1.0,   c(Zr)/(c(Zr)+c(Ti)) is in the range from 0.1 to 0.3,   c(Pb) is the lead concentration,   c(Zr) is a zirconium concentration, and   c(Ti) is a titanium concentration.   
     
     
         8 . The micromechanic structure according to  claim 1 , wherein the micromechanic structure is an infrared light sensor and/or an actuator. 
     
     
         9 . A method for making the micromechanic structure, the method comprising:
 providing the micromechanic structure according to  claim 1 ; and   arranging the ferroelectric layer on the first metal layer by a sputter process.   
     
     
         10 . The method according to  claim 9 , wherein the sputter process is a confocal sputter process. 
     
     
         11 . The method according to  claim 9 , further comprising:
 simultaneously depositing lead, zirconium, and titanium of the lead zirconate titanate from three different sputter targets, wherein each of the three different sputter targets includes only one of the lead, the zirconium, and the titanium.   
     
     
         12 . The method according to  claim 9 , further comprising:
 decreasing the lead concentration in the ferroelectric layer in the stepped manner with the increasing distance from the first metal layer by lowering only a sputter rate of the lead.   
     
     
         13 . The method according to  claim 9 , further comprising:
 decreasing the lead concentration in the ferroelectric layer in the stepped manner with the increasing distance from the first metal layer by lowering an electrical power applied on a sputter target that includes the lead.   
     
     
         14 . The method according to  claim 13 , wherein the electrical power applied on the sputter target that includes the lead is lowered starting from an electrical start power P max,lead  by a value in a range from 0.2 W to 2 W per a distance of 100 nm from the first metal layer. 
     
     
         15 . The method according to  claim 13 , wherein the electrical power applied on the sputter target that includes the lead is lowered starting from an electrical start power P max,lead  by a value of 1 W per a distance of 100 nm from the first metal layer.